8 Glasses Controversy

In a controversial report in the American Journal of Physiology, researcher Heinz Valtin, MD, a kidney specialist and author of two widely-used textbooks on the kidney and water balance, writes that he finds it "difficult to believe that evolution left us with a chronic water deficit that needs to be compensated by forcing a high fluid intake."

If you have trouble drinking this amount of water, you may already be getting enough liquids in the foods you eat and other beverages you drink. "People think they have to drink 8 eight-ounce glasses of water a day, when this has actually been the recommended amount of fluids," explains Jo Ann Heslin, RD. "Fluid intake can include water, mineral water, non-fat milk, or juice."

Any drink that does not contain caffeine counts toward daily intake, explains Heslin, who in addition adds: "We get a good amount of fluid in the foods we eat."

Other experts allow caffeinated and alcoholic beverages toward the count.

Dr. Valtin believes the notion began as a misinterpretation of the recommendation by the Food and Nutrition Board of the National Research Council, which suggested "1 milliliter of water for each calorie of food" (about 60 to 80 ounces). Although the Board added that "most of this quantity is contained in prepared foods," he points out this qualifier seemed to be overlooked, and thus the 8 x 8 rule was perpetuated.

"I have found no scientific proof that absolutely every person must drink at least eight glasses of water a day," says Dr. Valtin. On the contrary, he says, some studies have shown that caffeinated drinks, such as most coffee, tea, and soft drinks -- and, to a lesser extent, even alcoholic beverages such as beer, if taken in moderation -- could count toward the daily total.